<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
   <a href="/javaweb/ParamServlet?username=tom&password=123"> click </a>
   <p>
   <form  action="HelloServlet" method="post">
       <input name="id" type="hidden" value="1">
      <input name="username">
      <input name="password" type="password">
      <input name="age"><br>
      <input type="checkbox" name="ball"  autocomplete="off" />A
       <input type="checkbox" name="ball" value="B" autocomplete="off" />B
       <input type="checkbox" name="ball" value="C" autocomplete="off" />C
      
      <input type="submit">
   </form>
    
</body>
</html>